For examination of objects of interest with electromagnetic radiation, visible or invisible light or X-rays may be used. The method disclosed in Pfeiffer et al. “Phase retrieval and differential phase-contrast imaging with low-brilliance X-ray sources”, Nature Physics 2006 in the domain of X-ray differential phase-contrast imaging (DPC) is based on an extension of Talbot interferometry. The extension consists of adding a third grating allowing the use of a poly-chromatic X-ray spectrum. The gratings used in this technique are formed by linear trench arrangements, as depicted in FIGS. 1 and 2. The detection of intensity variations via phase stepping allows the measurement of the phase gradient of the X-ray wave front perpendicular to the trenches of the grating.
However, in order to provide for an image of reasonably well quality, an appropriate positioning accuracy while stepping and a non trivial phase retrieval may have to be performed.